| Index | Built | Description |
| SA.1 | Y | Sturgeon PR.Mk.1 |
| SA.2 | Y | Sturgeon TT.Mk.2 |
| SA.3 | | Projected naval jet fighter to N.7/46, Hawker Seahawk won |
| SA.4 | Y | Sperrin |
| SA.5 | | Projected four-engined transport to 8/46, AW Apollo won |
| SA.6 | Y | Sealand |
| SA.7 | | Projected training / light transport seaplane |
| SA.8 | | Projected civil Shetland derivative with Nomad engines |
| SA.9 | | Projected military assault glider to X.30/46 |
|
| SB.1 | Y | Sherpa, glider configuration |
| SB.2 | | Sealand II with Leonides engines, one not completed as such |
| SB.3 | Y | Sturgeon ASW variant |
| SB.4 | Y | Sherpa, powered configuration |
| SB.5 | Y | Wing-sweep testbed |
| SB.6 | Y | Seamew |
| SB.7 | Y | Sealand III |
| SB.8 | | Projected rigid-hub AOP helicopter to HR.144T, Fairey Ultralight won |
| SB.9 | Y | Sturgeon TT.Mk.3 |
|
| SC.1 | Y | VTOL flat-riser |
| SC.2 | |
| SC.3 | |
| SC.4 | Y | Canberra U.Mk.10 conversions |
| SC.5 | Y | Belfast |
| SC.6 | Y | Canberra U.Mk.14 conversions |
| SC.7 | Y | Skyvan |
| SC.8 | | |
| SC.9 | Y | Canberra PR.Mk.9 XH132 converted to testbed |
|
| SD.1 | Y | Canberra PR.Mk.3 WE416 converted to launch SD.2 |
| SD.2 | Y | Stiletto |
| SD.3 | Y | 3-30 and 3-60 airliners |